Going Triple-Sonic

Forty-five years ago this month, the USAF/North American XB-70A Valkyrie reached three times the speed of sound for the first time. The historic aviation achievement took place on the 18th anniversary of the breaking of the sound barrier by the USAF/Vell XS-1.

When it comes to legendary aircraft, aviation enthusiasts speak in almost reverent terms about the XB-70A Valkyrie. Indeed, few aircraft have evoked such utter awe or symbolized better the profound majesty of flight than the “The Great White Bird”. Though its flight history was brief, the XB-70A’s influence on aviation has proven to be of enduring worth.

The Valkyrie measured 185 feet in length, had a wingspan of 105 feet and an empty weight of 210,000 pounds. With a GTOW of 550,000 pounds, it was the heaviest supersonic-capable aircraft of all-time. The aircraft was powered by a six-pack of General Electric YJ93-GE-3 turbojets totaling 172,200 pounds of thrust in afterburner.

To enhance lift-to-drag ratio and directional stability at high Mach number, the Valkyrie was configured with wing tips that could be deflected downward as much as 65 degrees. Each wing tip was the size of an USAF/Convair B-58A Hustler wing panel. To this day, the XB-70A deflectable wing tip is the largest control surface ever used on an aircraft.

The XB-70A was originally intended to be a supersonic strategic bomber. The aircraft’s mission was to penetrate Soviet airspace at Mach 3 and deliver nuclear ordnance from an altitude of 72,000 feet. However, the rapid ascendancy of Soviet surface-to-air missile capability would compromise the type’s military mission before it even flew.

As a consequence of the above, the Valkyrie ultimately became a high-speed flight research aircraft. Only two (2) copies were constructed and flown. Ship No. 1 (S/N 62-0001) made its maiden flight on Monday, 21 September 1964 while Ship No. 2 (62-0207) first took to the air on Saturday, 17 July 1965.

XB-70A Ship No. 1 became the first Valkyrie to hit Mach 3. It did so while flying at an altitude of 70,000 feet on Thursday, 14 October 1965. The flight crew consisted of North American Aviation test pilot Alvin S. White (aircraft commander) and USAF Colonel Joseph Cotton (co-pilot).

The XB-70A aircraft flew all of their flight research missions out of Edwards Air Force Base in California. Between September of 1964 and February of 1969, a total of 129 XB-70A research flights took places; 83 by Ship No. 1 and 46 by Ship No. 2. A total of nearly 253 flight hours was amassed by the aircraft.

The XB-70A Program made significant contributions to high-speed aircraft technology including aerodynamics, aerodynamic heating, flight controls, structures, materials, and air-breathing propulsion. Lessons-learned from its flight research have been applied to numerous aircraft developments including the B-1A, American SST, Concorde and the TU-144.

XB-70A Ship No. 1 survived the flight test program while Ship No. 2 did not. The latter was destroyed in a mid-air collision with a NASA F-104N on Wednesday, 08 June 1966. Today, XB-70A Ship No. 1 can be seen at the National Museum of the United States Air Force at Wright-Patterson Air Force Base in Dayton, Ohio.